Electronic devices including game devices and home appliances that are available in recent years provide significantly advanced functions. In association with this, the system that allows a user to provide an input through a user interface has become increasingly complicated. Various improvements have been made to user interface so that a use can provide an input easily using such a complicated input system. For example, attempts have been made to use different approaches to assignment of functions to controller buttons or to use a touch panel. Also proposed are technologies that use an image capturing device designed to capture an image of the user as a user interface so as to initiate various events by detecting the state of the user's face (see, for example, patent document No. 1).
By using an image capturing device as a user interface, an ordinary face recognition technology can be used to detect the state of the user's face. For example, a matching score may be computed between a reference image prepared in advance and an image of a detected facial region. Alternatively, the orientation or tilt of a face is determined by referring to the area of a facial region.
Details of certain systems and devices may be found in JP 2008-15942.
In association with the advancement in information processing technology and diversification in environments in which electronic devices or information processing devices are used, in users, and in processing details, different user interfaces are required depending on the factor that causes the difference. Therefore, the mode of user interface should be more diversified to capture such needs. In particular, there is called for a user interface that allows a user to provide an input through a more natural movement without experiencing a complex process of, for example, providing an input using a large number of buttons.